Riluzole is FDA-approved for the treatment of which condition?

Riluzole is FDA-approved specifically for the treatment of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease that affects motor neurons in the brain and spinal cord. Its mechanism of action involves the inhibition of glutamate release and modulation of glutamate receptors, which are thought to play a role in the neurotoxicity associated with ALS.

In the case of ALS, riluzole is the first drug approved that has been shown to extend survival and time to tracheostomy in some patients. This makes it particularly relevant in the management of the disease, as there are few options available for halting or slowing the progression of ALS.

The other conditions listed do not have riluzole as a treatment option. For instance, Parkinson's disease and Alzheimer's disease have their own sets of treatments that focus on different neurotransmitter systems and symptomatic management, while multiple sclerosis is primarily treated with immunomodulatory therapies. Riluzole's specific role in ALS sets it apart as the correct answer in this context.